There is known from European patent No. 0 384 850, in the name of the same applicants, a particularly satisfactory immobilization device.
This device, in one of its modifications, comprises an assembly of chocks articulated in a fixed structure, a connected metal frame or a masonry casing for example, to ensure an integration at the site of use. These chocks each comprise a base, mounted pivotally relative to this fixed structure, a safety member, provided to coact with the safety member of the adjacent chock by assuring locking, and an actuator, in this case a pneumatic jack.
The operation of this device is as follows:
1/when the vehicle moves in reverse toward a loading dock for example, the chocks retract one after the other under the passage of the wheels, PA1 when in loading/unloading position, chock No. 1 immediately in front of the wheel is raised because the pneumatic jack is subjected to a residual pressure which ensures the permanent raising of the chock but which gives rise to a power substantially lower than the pressure of the wheel on the ground, and chock No. 2 is retracted beneath the wheel, PA1 when the wheel moves very slightly forward toward chock No. 1, a pedal actuated by the wheel, projecting from the surface of each chock and hence from this chock No. 1, ensures the displacement of a blocking lever which coacts with a lug carried by the adjacent chock No. 2, which is located below the wheel in the retracted position, such that the chock No. 1 is blocked in raised position while chock No. 2 is retracted by the wheel. PA1 2/When the vehicle must be released, it is first of all necessary that the vehicle retreat slightly to free the actuator pedal and hence the lock, then the jacks are all actuated simultaneously to retract the assembly of the chocks which are then unlocked relative to each other.
It will be noted that this device is particularly attractive because the blocking is automatic and requires no manual or deliberate intervention. Moreover, self-blocking is ensured by a pair of chocks, the one beneath the wheel and the adjacent one, but if the vehicle were to escape by an uncontrolled movement of the first pair of chocks, it would be blocked by the following ones which would be self-blocking.
The fact remains, however, that the device requires a relatively precise in situ mounting such that the pedals, the actuating levers and the lugs will be correctly positioned relative to each other, so as to ensure reliable locking at the desired moment but also reliable unlocking at the time of freeing the vehicle.
Moreover, this locking of the chocks to each other is not necessarily practical for modularity of the installations.
The vehicles are also provided with wheels having all sorts of diameters, which makes it very difficult to dimension the chocks when they are connected to each other to ensure locking.
Such devices are undoubtedly interesting but there remains a barrier to be crossed, that of the investment which represents the equipment of the different loading ramps of industrial unit, so that it is necessary to reduce the cost of production on the one hand and to decrease the cost of installation on the other hand.
To decrease the cost of installation, it is necessary to decrease the number of constituent elements, it is necessary to use commercially available parts for the essentials and it is necessary to permit complete accessibility to each of the chocks independently.
If the device with a set of chocks according to the prior art gives satisfaction, there nevertheless exists the requirement for modular self-contained and automatic chocks and it is the object of the invention to provide such a modular chock, adapted to be associated with other adjacent chocks to form a modular immobilizing device, which operates in an entirely automatic and self-contained manner, which is easy to make, and hence less costly, which uses commercially available parts and whose installation is rendered very easy by the arrangement of the elements which comprise this self-contained chock and by the accessibility which it gives.